Relationship between fluorodeoxyglucose uptake in the large vessels and late aortic diameter in giant cell arteritis.

OBJECTIVE: GCA carries an increased risk of developing thoracic aortic aneurysms. Previous work with fluorodeoxyglucose (FDG)-PET has shown that the aorta is frequently involved in this type of vasculitis. We wanted to investigate whether there is a correlation between the extent of vascular FDG uptake during the acute phase of GCA and the aortic diameter at late follow-up. METHODS: All patients with biopsy-proven GCA who ever underwent an FDG-PET scan in our centre were asked to undergo a CT scan of the aorta. The diameter of the aorta was measured at six different levels (ascending aorta, aortic arch, descending aorta, abdominal suprarenal, juxtarenal and infrarenal aorta) and the volumes of the thoracic and of the abdominal aorta were calculated. RESULTS: Forty-six patients agreed to participate (32 females, 14 males). A mean of 46.7 +/- 29.9 months elapsed between diagnosis and CT scan. All aortic dimensions were significantly smaller in women than in men, except for the diameter of the ascending aorta. Patients who had an increased FDG uptake in the aorta at diagnosis of GCA, had a significantly larger diameter of the ascending aorta (P = 0.025) and descending aorta (P = 0.044) and a significantly larger volume of the thoracic aorta (P = 0.029). In multivariate analysis, FDG uptake at the thoracic aorta was associated with late volume of the thoracic aorta (P = 0.039). CONCLUSION: GCA-patients with increased FDG uptake in the aorta may be more prone to develop thoracic aortic dilatation than GCA patients without this sign of aortic involvement.

Additional value of integrated PET-CT in the detection and characterization of lung metastases: correlation with CT alone and PET alone.

The purpose was evaluating retrospectively the additional value of integrated positron emission tomography (PET) and computed tomography (CT) in the detection of pulmonary metastases in comparison with CT and PET alone. Fifty-six lung nodules, divided into three groups according their size, detected in 24 consecutive patients with a known primary tumor were retrospectively evaluated with integrated PET-CT, CT and PET. The nature of these nodules was determined by either histopathology or a follow-up of at least 6 months. The CT and PET images of the integrated PET-CT were evaluated separately by a radiologist and a nuclear medicine physician, the integrated PET-CT images were evaluated by a chest radiologist and nuclear medicine physician in consensus. The investigators were asked to search lung nodules and to determine whether these nodules were metastases or not. Sensitivity and accuracy for CT, PET and integrated PET-CT for characterization of all pulmonary nodules were, respectively: 100%, 90%, 100% and 57%, 55%, 55%. There was no significant difference in the characterization of pulmonary nodules between integrated PET-CT and CT alone (P=1.000) and PET alone (P=0.1306). An accurate evaluation is only possible for lesions larger than 1 cm.

Repetitive 18-fluorodeoxyglucose positron emission tomography in isolated polymyalgia rheumatica: a prospective study in 35 patients.

OBJECTIVE: To study fluorodeoxyglucose (FDG) deposition in different vascular beds and in the large joints of patients with isolated polymyalgia rheumatica (PMR), and to investigate whether there is a relation between FDG-positron emission tomography (PET) results and risk of relapse. METHODS: All consecutive patients with isolated PMR underwent a FDG-PET scan before treatment with steroids was started and--if logistics allowed--at 3 and 6 months. PET scans were scored at seven different vascular areas and a total vascular score (TVS) was calculated, ranging from 0 to 21. FDG uptake in the shoulders, the hips and the processi spinosi of the vertebrae was scored as 0 (no uptake), 1 (moderate uptake) or 2 (intense uptake). RESULTS: Thirty-five patients entered the study. At diagnosis, vascular FDG uptake was noted in 11 patients (31%), predominantly at the subclavian arteries. Mean TVS was low. FDG uptake in the shoulders was noted in 94% of patients, in the hips in 89% and in the processi spinosi of the vertebrae in 51%. The intensity of FDG uptake in the large vessels or in the shoulders, hips or processi spinosi did not correlate with the risk of relapse. CONCLUSIONS: Only one in three patients has an (moderately) increased vascular FDG uptake, especially in the subclavian arteries. The vast majority has inflammation of shoulders and hips, and half of them have increased FDG-uptake at the processi spinosi. Results of FDG-PET scans in patients with PMR did not correlate with their risk of relapse.

Dopamine transporter SPECT using fast kinetic ligands: 123I-FP-beta-CIT versus 99mTc-TRODAT-1.

A comparative study was carried out on two promising presynaptic dopamine transporter single-photon emission tomography (SPECT) radioligands with a fast pharmacokinetic profile, 123I-FP-beta-CIT (FP) and 99mTc-TRODAT-1 (TR), in order to assess their differential diagnostic power in early parkinsonism and their sensitivity for detection of disease progression. This cross-sectional study was conducted on 96 patients with early-stage parkinsonism referred in a tertiary clinical setting. Mean disease duration was 2.0+/-1.3 years, and patients had a modified Hoehn and Yahr (H&Y) stage of 1-2 (average 1.2). Forty-seven patients received TR, and 49 received FP. In both groups, ten patients with normal presynaptic function were included as a control population; all other patients were clinically diagnosed as having idiopathic Parkinson's disease. Groups were matched for gender, age, disease duration and modified H&Y stage. Triple-head gamma camera SPECT was analysed using a semiquantitative index of transporter binding (BI). Discriminant analysis with cross-validation resulted in a maximal classification accuracy for FP of 93% (sensitivity 95% and specificity 86%) for the contralateral putamen BI. For TR, the corresponding values were 87% accuracy, 92% sensitivity and 70% specificity. For FP, disease duration was correlated with both the putamen BI (-8.8%/year, rho=-0.41, P=0.025) and the putamen/caudate ratio (-7.4%/year, rho=-0.51, P=0.004), but for TR no significant correlation was found (all P values >0.5). In conclusion, both FP and TR show high sensitivity in a clinically relevant setting, but FP has superior accuracy for early differential diagnosis of idiopathic parkinsonism and non-degenerative extrapyramidal disorders, as well as better sensitivity for disease follow-up.